IGListKit
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ListSectionController's didUpdate and cellForItem re-called, even though isEqual == true
New issue checklist
- [x] I have reviewed the
README
and documentation - [x] I have searched existing issues and this is not a duplicate
- [x] I have attempted to reproduce the issue and include an example project.
General information
-
IGListKit
version: master - iOS version(s): 13.6
- CocoaPods/Carthage version: Carthage latest
- Xcode version: 11.6
- Devices/Simulators affected: iPhone device and simulator
- Reproducible in the demo project? (Yes/No): No?
- Related issues: -
Debug information
import IGListKit
class ContentItem: ListDiffable {
weak var item: Content?
weak var section: ContentSectionController?
func isEqual(toDiffableObject object: ListDiffable?) -> Bool {
return true
}
init(item: Content?) {
self.item = item
}
}
class ContentSectionController: ListSectionController {
weak var object: ContentItem?
override func didUpdate(to object: Any) {
self.object = object as? ContentItem
self.object?.section = self
// should only be called on updates
}
override func sizeForItem(at index: Int) -> CGSize {
guard let content = object?.item else {
return CGSize(width: 0, height: 0)
}
// calculate height
}
override func cellForItem(at index: Int) -> UICollectionViewCell {
let cell = collectionContext!.dequeueReusableCellFromStoryboard(withIdentifier: "ContentCell", for: self, at: index)
(cell as? ContentCell)?.item = object // didSet will update cell
return cell
}
override init() {
super.init()
self.workingRangeDelegate = self
}
}
extension ContentSectionController: ListWorkingRangeDelegate {
func listAdapter(_ listAdapter: ListAdapter, sectionControllerWillEnterWorkingRange sectionController: ListSectionController) {
// prepare
}
func listAdapter(_ listAdapter: ListAdapter, sectionControllerDidExitWorkingRange sectionController: ListSectionController) {
return
}
}
class ContentDataSource: NSObject {
static let sharedInstance = ContentDataSource()
var items: [ContentItem] {
return Content.displayItems.map { ContentItem(item: $0) }
}
}
extension ContentDataSource: ListAdapterDataSource {
func objects(for listAdapter: ListAdapter) -> [ListDiffable] {
return items
}
func listAdapter(_ listAdapter: ListAdapter, sectionControllerFor object: Any) -> ListSectionController {
return ContentSectionController()
}
func emptyView(for listAdapter: ListAdapter) -> UIView? {
return nil
}
}
/// VC ///
class ContentViewController: UIViewController {
@IBOutlet weak var collectionView: UICollectionView!
override func viewDidLoad() {
super.viewDidLoad()
let updater = ListAdapterUpdater()
adapter = ListAdapter(updater: updater, viewController: self, workingRangeSize: 2)
adapter.collectionView = collectionView
adapter.dataSource = ContentDataSource.sharedInstance
}
var adapter: ListAdapter!
override func viewDidAppear(_ animated: Bool) {
super.viewDidAppear(animated)
adapter.performUpdates(animated: true)
}
// ...
}
On every view appear I call adapter.performUpdates(animated: true)
, which should never update the cells since isEqual
is overridden with true
. Nonetheless, all cells' didUpdate
is triggered, calling cellForItem
again too.